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Topic 53: Health, safety, environmental and cost issues regarding operation, disposal, and re-use of decommisioned plants

Azeezat's picture

In some years to come a large proportion of the offshore
platform will need to be decommissioned. Can we discuss the health, safety, environmental and cost issues as
regards the operation,disposal, and any potential re-use of decommisioned plants and structures?

Comments

Azeezat's picture

Decommissioning in the oil and gas is cessation of well
operations, removal of plants and equipment, removal or partial removal of any
structure or platforms and making good the seabed.

In determining the best strategy for decommissioning of any
installation there should be a balance between the technical difficulty and
safety, impact on the environment and cost.

For any decommissioning process there should be an
appropriate balance between safety, environmental and financial risk. The
solution to all these factors should be planned to have minimal environmental
consequence and workforce.

Before decommission is commenced, the hazards need to be
identified and assessed. The physical hazards types from decommission are toxic
materials, explosive material, object with high potential energy, object with
high potential energy, objects with high kinetic energy, dangerous
microbiological substance.

For any decommissioning process there is likelihood of
failure consequences which could be as a result of the hazards highlighted
above and other hazards which the consequences include death, injury to
workforce, physical damage to engineering system, loss of use of facility, loss
of professional reputation.

In any decommissioning process there are factors resulting
from this which are technical feasibility of the proposed plan, environmental
impact, economic impact, public concern and potential impact on human health
and safety.

The disposal and dismantling of the decommissioned plant and
structures also posses engineering and environmental hazards which must be
considered carefully. The safety of personnel, such as mechanics, welders,
riggers, electricians and divers, is of paramount importance. Any
decommissioning option must seek to minimize the hazards of operations such as
underwater cutting and cleaning of vessels.

Reference:

Decommissioning Offshore Structures by Gorman, D.G.;
Neilson, June (Eds.)

Trevor Strawbridge's picture

The eyes of the world will be on methods we adopt for decommissioning. Although I think the UKCS is ahead of the rest of the world here, I think we still have a journey to travel to obtain solutions that will satisfy the industry and the environment. I am interested to see where the hardwhere will be taken too and how will it be disposed of and if possible recycled. At present we are only witnessing a small proportion of the inevitable scrap metal platforms, pipelines and other structures that are coming our way. There has already been opposition to decommissioning of 2 former WW2 war ships, "but" they have to be disposed of. DECC has a website with some guidance for the operators and contractors although it seems to focus more on the regulations. There is extensive reference to OSPAR (Oslo & Paris Convention on protection of Marine Environment. See Links below

 

http://og.decc.gov.uk/en/olgs/cms/explorationpro/decommissionin/decommissionin.aspx

 

Trevor

Craig Donaldson's picture

In my view as long the operator has done research into possible re-use methods for their plants or platforms and submitted their case to the appropriate regulator for approval (similar to the ones in the link at the bottom from DECC) then you cannot expect them to do anymore. The costs involved in decommissioning can be enormous and more often than not for no financial gain to the company. In other words companies are not doing this because they want to but only because they have to. If they do not do it they face fines (likely to be much less than the cost of decommissioning the facility) and likely court appearances. Obviously the reason they do it is show that they are environmentally responsible and thus to retain or even increase their international reputation. Therefore, the proper regulation has to be in place to ensure the companies act in a meaningful manner. 

Regulation about decommissioning should be in place before the design of platforms begins in order for the designers to consider the ease of removal of such facilities at the end of their life. Unfortunately it is too late for the UKCS but it should be implemented as soon as possible in new and upcoming oil & gas industries in countries such as Cyprus, Ghana and Kenya. If decommissioning had been though about while facilities were designed in the seventies then we wouldn't have ended up with platforms that have giant concrete legs and bases which are now more or less immovable. Cormorant Alpha is an example of this.

http://og.decc.gov.uk/en/olgs/cms/explorationpro/decommissionin/table_de...

AndrewRCarss's picture

Hi Craig,

Your second point on the design of platforms to facilitate their easy removal is an interesting one. It’s not just the technical challenges associated with the removal of redundant platforms, but the safety considerations also.

If you are to read the BP North West Hutton Decommissioning Report, p14, the potential loss of life  (PLL) ratio is as high as 1 in 600 for a diver involved in the full removal of a subsea jacket. This risk is of course total unacceptable

In 1964 the Geneva Convention came into force initiating requirements to regulate offshore developments and remove any disused structures. So if oil companies knew they would have to remove them, why have many of them been built, such as the Cormorant Alpha platform you mention? It also makes me wonder why the CDM regulations do not apply when you get 12miles offshore. The Construction Design Management Regulation  (CDM) are used in the construction industry to ensure safety considerations, throughout the life of a structure [Operation, maintenance and decommissioning], are taken into consideration at the design stage.  James Munroe touched on this briefly in lecture number 7 but did not go into it much.

Perhaps legislation similar in nature to the CDM regulations should apply to offshore structures.

Andrew Carss - MSc Subsea Engineering (DL)

Siwei Kang's picture

With the aging of the platforms and other subsea infrastructure, the decommissioning industry is evident and has huge potential in the future. It is estimated that there are more than 300 offshore platforms in the UK which has already served over 15 years. Around 50 olatforms will cease production by 2016. The decommissioning cost in the North Sea will be up tp 30 billion in the next 30 years. 

On the other hand, the challenges exist in many areas during decommissioning. For environment, leakage could be related with the operating activities when transportaion and storage. The unpropriated abandoned wells could regain the pressure to cause oil spill. meanwhile, all the removal methods for decommissioing consume energy. For health and safety, the risks in persons involved with activities, heavy lift vessels, diving activities, cutting activities and so on neec to be considered. Cost always gives the operator burden despite it has been budgeted before platform construction. The inflation of materials, day rate of vessels and uncertain things can make cost overrun.

However, it also brings new chance to the operator. Developing renewables, like wind turbine, wave or tidal, and building reserch center will be a better choice for reusing aging platforms. This may create profits. Some platforms were transferred to power generation to supply electricity to their nearby platforms.

In a word, challenge and chance are existing for decommissioning.

Dike Nwabueze Chinedu.'s picture

The process of decommisioning si as important as commisioning or constrcution. This is because of its safety, health and environmental implications as well as the cost implications.To abide by the set standards and regulations governing decommisioning, the management organisational readiness must be backed with the relevant resources. The marine environment will sure be affected, and the health and safety of the project personnel is paramount.


When an offshore platform is decommissioned, it is either reused, reused for quay construction, removed to shore, or toppled over to sea.
It is always good to reuse such structure for quay contrsuction because of the financial benefits and environmental benefits.


The decommisioned of platform is gaining more awareness as most of the offshore platforms get to the end of thier useful life. Thus, financial consideration is not always the consideration in a decommissioning project.

charlesggeorge's picture

Mostly in decommissioning,
the environmental perspective effects is 
due to  with removal process of
the platform. Steel, aluminium, zinc, cadmium and residual process oil over
decades are possible to have a toxic affect the marine environment. For concrete
installations in the platforms, these are potentially less polluting than their
steel counterparts because of their longer life span and the fact that they are
less susceptible to leaching. Heavy metals cannot be absorbed into the
ecosystem and thus comprise enduring risk. It is clear that there will be negative
impact which affect marine flora and fauna because of heavy metals like lead,
zinc, mercury and cadmium which is not dissolved or decomposed in the environment.

Alabi Ochu Abdulraheem's picture

Offshore decommissioning activity is on the high side as existing field infrastructures approach the end of their useful life. One of the major challenges faced in decommissioning is the inhospitable environment encountered in the removal of heavy structures. There are legislation governing offshore decommissioning activities with the aim of maintaining complete compliance and operational best practice. In order to reduce field development cost, platform reuse is an ideal option. Before a decommissioned plant can be put into efficient reuse (that is back into operations), all threats associated with it should be assessed in the risk assessment program of an integrity management plan. Example of threats associated with decommissioned plant are corrosion, defects and materials.
References
1) http://www.iev-group.com/index.php?mid=5027
2) http://www.pipeline-conference.com/sites/default/files/papers/Rabindran_0.pdf
Name: Alabi Ochu Abdulraheem
Reg no: 51231595

faizakhatri's picture

 Risk associated with Decommissioning of aged platform is depend upon size, type, depth, condition and location of particular platform  the whole process of decommissioning there are  a lot of technological, operational, procedural and environmental risk associated  which required  hazard management strategy involving a clear risk management plan complimented with good HSE regulation. Decommissioning activities start  with well abandonment in which  cleaning and disconnections of other facilities can be done after that removing of  topside in which including  lifting and transportation of heavy sections, cutting of heavy steel structures, which need manpower and heavy cranes  it may be possible that some Subsea noise and disturbance to the habitant as a result of this activity and after that  jacket  removal there are lot of safest technologies being used in these days and industry still looking for better  approach to ensure cost effective management and mitigate of various Health safety and environment  risks. And applied ‘Reduce, recycle and re-use’ practices more  Reference:http://og.decc.gov.uk/en/olgs/cms/explorationpro/decommissionin/decommissionin.aspxhttp://www.offshore-technology.com/features/feature79640 Faiza KhatriM.Sc oil and gas engineering  

 

Savitha Haneef's picture

In line with Siwei Kang,I would like to add some more challenges to be faced.While decommisioning ,there would be hazardous chemicals accumulated in the pipeworks.Disposing them safely is going to be a big challenge.Would oil companies be ready to manage and dispose them safely?.Disposing safely and minimising cost is a contradictory requirement.It is definite that cost is going to shoot up.The question is would they compromise on the safety?The way in which decommissioning projects handled by oil companies are going to be lumpsome.Another challenge to be faced would be with the dismantled structures. Are there enough capacities available to accept these structures?. Re-using them would be a better option.More and more research needs to be done in re-using these structures.Citing previous cases,decommissioning of gravity based platforms are quite challenging.The fact that there is no provision for cleaning of the storage tank leads to abandoning them which potentially involves many risks and hazards.Dealing with old machineries and unreliable equipments is going to push safety to its limits.

 

Savitha Haneef
MSC Safety & Reliability Engineering

 

The
reuse of aged oil platforms as related to decommissioning is a great idea which
has been in use in US Gulf of Mexico. This idea works in two folds as
highlighted by 
R. C.
(Bob) Byrd, J. R. (Ron) Twachtman (1998):

1. Seller of the platform has
opportunity to maximise return on their capital investment even after years of
operational life and also eliminate the cost of decommissioning the platform.

 2. For buyers, it provides
a cost effective means and also generate faster schedule since the platform was
an already used operating one.

For
the environment, the platform serves as source of accommodation for some
animals, and also remove the idea of water pollution during decommission
process. 

Wind turbine farms are most
likely the industries that are common in the reuse of platforms. currently,
windturbines are also designed alongside with new generation platform as a
source of energy to the platform.

There are issues raised
concerning the reuse of such facilities, especially from the engineering and environmental
point of view. concerns raised include and not limited to re-designing of the
facility to accommodate extra weight putting into design consideration its life
cycle, fatigue and impact stress concentration limit at offshore, also the time
taken to re-access already used platform.

From
the environmental point of view, most especially facilities already used
offshore will not meet the current health and safety standard. 

 

 

References:

1.      
http://www.offshore-mag.com/articles/print/volume-58/issue-11/departments/drilling-production/maximizing-platform-value-minimizing-decommissioning-costs.html

2.      
http://www.greentechmedia.com/articles/read/when-oil-rig-met-wind-turbine-5692/

 

 

 

Uko Bassey's picture

There are different approaches used in decommissioning offshore platform installations. These include:

1. Leave in situ - leaving the structure in situ after cleaning of all hydrocarbons while the individual components like topside, jackets can be removed and it is considered separately.

2. Monitoring - which is the same as leaving in situ but with an on-going monitoring programme.

3. Toppling - which is done by falling the structure to lie on its side on the site.

4. Shallow disposal - which is dismantling the structure and deposited on the seabed around the site.

5. Return to shore - this is a recovery method where the entire structure is dismantled and transported to shore.

The major concerns in decommissioning and disposal of aged offshore facilities and platforms are technical feasibility, risk to personnel (expressed in PLL and FAR), environmental impact (including societal impact), cost and shareholders’ interests.

Most times, the age of the equipment, and the uncertainties associated with their ongoing maintenance and logistical support, reduce their reuse potential. Also the difficulties in decommissioning and the various methods do not allow it for reuse.

The combined cost of decommissioning and transporting the decommissioned platform/structure to onshore or the next point of reuse may be as costly as the cost of installation with the foreseeable risks.

Uko Bassey's picture

 

Offshore decommissioning has both positive and negative impacts. The positive are in terms of maritime transport, employment generation, environmental associated benefits, etc. There many environmental issues associated with decommissioning which include but not limited to energy consumption, CO2 emissions, discharge to sea, littering, impact on free passage and on fisheries, etc. However, most issues are always low and insignificant in the environment.

Offshore platforms are often design life in excess of 30 years depending on the life of the field and prospective future tie-ins, of which safety of lives, environment and assets are ultimate. In respect of the above mentioned safety reasons, do we design platforms with the expectation of removal in future date? if yes, what are the major decommissioning factors considered when designing a platform? These questions are necessary in view of the risks and hazards in the offshore industry, harsh weather conditions (turbulent waves, wind and sea current, etc) associated in the industry and the previous experiences like "The Alexander Kielland in 1980", Petrobras P36 platform design, etc.

 

AndrewRCarss's picture

 

 

Hi Uko,

Your question on wither platforms should be designed with decommissioning in mind..this answer is most defiantly yes!

The OSPAR convention governs the decommissioning of platforms in the North-East Atlantic including the North Sea.  The convention forbids the dumping of whole, or part, of any disused structures in the marine environment.

This convention is an evolution of the Geneva Convention passed in 1964 which initiated requirements to remove disused offshore structures.

So what I am getting at is that there has been a requirement to remove these structures right from the start and the oil companies have known about this.

It seems to me, however, that the owners of the platforms have been wholly short-sighted in the design and construction of these facilities.

Decommissioning is an expensive, dangerous job, and the very companies that put the platforms there in the first place are now tasked with their decommissioning.

I am sure that due to the huge costs involved, that the oil companies, such as BP, have learned a very expensive lesson in not factoring the decommissioning into the designs.

Wither legislation to take decommissioning into account at the design stage is passed or not, I am certain that the operators will insist on it. This is because it is in their interest to do so from a commercial perspective if nothing else.

Andrew Carss - MSc Subsea Engineering (DL)

Felipe.Santana.Lima's picture

Decommissioning is most often a neglected subject during the engineering and design of production and process systems. Normally decommissioning will happen so far in the future that the net present value (NPV) of the associated costs normally is negligible, and therefore it is most often not considered in the engineering and design stage.

Whereas the NPV of decommissioning costs is often negligible, the day when the platform, module, subsea structure, etc needs to be decommissioned eventually comes, and the very viability of decommissioning theses systems in an HSE-friendly manner is not always guaranteed.

According to Blanchard and Fabrycky (2006) dedicate one entire chapter of their book to the subject “Design for producibility and disposability”. According to them, for any man-made system to be acceptably reliable, maintainable, usable, supportable, manufacturable and affordable, all life-cycle stages need to be addressed from conceptual design to system testing, verification and validation. The problem is that whilst systems engineering is concerned with all mentioned aspects of the system, not too seldom the key decision makers are only concerned with the latter: affordability. This influences the decision making process, even in the engineering process, to prioritise one or some aspects than others; and disposability often is not given the attention it needs. Sometimes the result is systems that for technical reasons cannot be decommissioned without major hazards, simply because this life-cycle stage was not thought through when the necessary provisions could be implemented.

Reference:

Blanchard S B and Fabrycky W J: “Systems engineering and analysis”, 2006.

Samuel Bamkefa's picture

Going on from the options available in decommissioning as outlined by Uko, I will like to add some insight into the economic and environmental implications of some.

An advantage of complete removal of structures to shore is that is gives a clear seabed. This will be benfeicial in areas where trawling is being carried out. Also, the possibility of recycling the components will also come into play. Sometimes though, a reuse without recycling can also be done. An example of this would be the potential use of disused oil pipelines for the transportation of CO2 for carbon sequestration

When structures are left in-situ however, the costs of energy and material to dismantle and take the stucture to shore is recovered. It should be noted however that the gains that can come from recyling or reuse are forfeited. Also, monitoring of the structure will take its own effort, and this has to be factored into the whole decommisioning costs. For pipelines, there are options of covering them or burying them. This will have reduced negative effect on trawling activities

The economics, safety and viability of the methods have to be weighed to choose the preferred option. The UK government for example has a provision for tax relief on decommissioning costs. This is there to further spur companies to take on decommissioning projects as the need arises

 

References

Paul Ekins, Robin Vanner and James Firebrace. 2005. DECOMMISSIONING SCENARIOS: A COMPARATIVE ASSESSMENT USING FLOW ANALYSIS.
Policy Studies Institute. Available on: http://www.psi.org.uk/docs/2005/UKOOA/Decommissioning-Working%20paper.pdf

 Samuel Bamkefa

amaka.ikeaka's picture

As oil and gas platforms approach the end of their useful lives, there's
need for the best strategy with regards to the decommissioning of these
platforms to be put in place. In order to overcome this technological and operational
challenge, the right balance must be achieved within health/safety,
environmental, technological and economical consideration. Decommissioning involves
the removal of offshore platforms and pipelines out of service, in an
environmentally safe and secure manner.  Before the commencement of this
activity, the installation process systems have to undergo depressurizing,
draining and cleaning. Clean decommissioned platforms contain heavy metals,
PCBs, and hydrocarbons. Left over structures in the marine environment will
corrode and leach contaminants into the marine ecosystem, which will accumulate
within fishes, and other marine organisms consumed in the human food chain [1].
In addition, the issue of disposing the installation once dismantled also poses
serious concerns.  With the onshore disposal option, transportation of
structures to land raises risk of collision or grounding near shore causing
significant environmental damage. On reaching the shore, the decommissioned structures
must be carefully disposed, as they contain many toxic chemicals and materials.
Disposal in land fill is not recommended, as it can result in contamination of
drinking or ground water in the future within the local area.  While
recycling these structures, removal of the marine growth attached to these
platforms will cause odor, noise and atmospheric disturbance to the local
communities. It is necessary to achieve the right balance within safety,
environment, technical capability and cost while carrying out the
decommissioning process.

Reference

[1] Environmental Risk and Decommissioning of Offshore Oil Platforms in
Nigeria

amaka.ikeaka's picture

As oil and gas platforms approach the end of their useful lives, there's
need for the best strategy with regards to the decommissioning of these
platforms to be put in place. In order to overcome this technological and operational
challenge, the right balance must be achieved within health/safety,
environmental, technological and economical consideration. Decommissioning involves
the removal of offshore platforms and pipelines out of service, in an
environmentally safe and secure manner.  Before the commencement of this
activity, the installation process systems have to undergo depressurizing,
draining and cleaning. Clean decommissioned platforms contain heavy metals,
PCBs, and hydrocarbons. Left over structures in the marine environment will
corrode and leach contaminants into the marine ecosystem, which will accumulate
within fishes, and other marine organisms consumed in the human food chain [1].
In addition, the issue of disposing the installation once dismantled also poses
serious concerns.  With the onshore disposal option, transportation of
structures to land raises risk of collision or grounding near shore causing
significant environmental damage. On reaching the shore, the decommissioned structures
must be carefully disposed, as they contain many toxic chemicals and materials.
Disposal in land fill is not recommended, as it can result in contamination of
drinking or ground water in the future within the local area.  While
recycling these structures, removal of the marine growth attached to these
platforms will cause odor, noise and atmospheric disturbance to the local
communities. It is necessary to achieve the right balance within safety,
environment, technical capability and cost while carrying out the
decommissioning process.

Reference

[1] Environmental Risk and Decommissioning of Offshore Oil Platforms in
Nigeria

Edwin Lawrance's picture

The challenges associated with decommissioning depend largely
upon the type of structure to be decommissioned. To decommission a platform there
are several HSE regulations to follow. Nowadays offshore structures are
designed to remove easily when the field is no longer live. But if the old platforms
are considered the decommissioning process won’t be easy. At the start of
decommissioning the well is plugged, subsea pipelines are flushed and all the hydrocarbon
presence is cleared by filling inert gases. This cleaned structure is then
dismantled and is towed to the land.

During these process of cutting, dismantling, cleaning etc.
can cause the surroundings to get polluted. The noise created during the decommissioning
can cause disturbance to the aquatic life. In the case of a fixed steel
platform a part of the footing s is left in the seabed, recovery of this part
is difficult and involves high risks. These leftovers are effectively made in
to artificial reefs for the marine life. Such places are marked with markers
for easy identification. During the scrapping of the platform onshore, land
pollution can happen. Day by day the risks and challenges associated with
decommissioning is reducing. 

Connie Shellcock's picture


In Ekins et al study of decommissioning of offshore
oil and gas facilities, they describe a typical North Sea Large steel deep
water structure consisting of the following ; a topside, a jacket, the footings
and the drill cuttings, each of which need to be disposed of when they reach
the end. In this study it is concluded that each of these 4 major parts will be
treated differently when it comes to decommissioning. Topsides will have to be
ashore as it is thought that this has less environmental impacts compared
leaving in situ. This however is more expensive. The jacket will have the same
outcome, except that it is a lot cheaper to take the jacket ashore. The footing
however will possibly stay in situ as it is thought that removing them has
massive safety concerns and will also be detrimental to the environment.
However leaving them in situ may have negative effects on other industries such
as fishing. What to do with drill cuttings is still part of a controversial
debate as to what is financially feasible and environmental friendly. This
source and many previous posts on this blog illustrate that there is a great
deal of uncertainty in decommissioning activities.
(Ekins, Vanner
et al. 2006)

 


Kyle McFarlane's picture

In the oil and gas sector it is likely that assets will only be decommissioned provided the fields and wells they are working on are no longer financially viable or if the assets condition has reached too low a level to be worth maintaining.
The majority of assets with undergo life extension programmes in order to increase their design life and therefore ensure that production continues for as long as possible, at as low a price as possible whilst adhering to safety regulations.
In 2010 the HSE launched Key Programme 4 which is the "age and life extension programme" the fact that this programme has been launched shows the extent of the assets likely to be extended.
The decommissioned assets will provide a valuable insight to the condition of offshore plant and equipment and hopefully how these can be better managed to ensure that assets can be designed to last longer.

Source
http://www.hse.gov.uk/offshore/ageing.htm

 

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